Lavatory basin



FIG. 1 is a top perspective view of a lavatory basin showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a left side elevational view thereof, the right side being a mirror image of the left side;

FIG. 4 is a front elevational view threrof; and,

FIG. 5 is a rear elevational view thereof. 

The ornamental design for a lavatory basin, as shown and described. 